Along with the continuous development of modern sciences and technologies, 3D (three dimensional) display technologies also develop rapidly. 3D display technologies make use of the principle of human binocular parallax, in which the left and right eyes of a person receive different images taken from two different angles, and the brain superposes the images and regenerates image information which is perceived with a stereoscopic effect of front-back, up-down, left-right, far-near, etc. As a result, a viewer may watch a film or a video with highly realistic effect. In order to achieve such a stereoscopic effect on a flat display, the images of the left and right eyes (interchangeably referred as “left-eye image”, “right-eye image” hereinafter) have to be separated. At present, the 3D display technologies are used in cooperation with 3D glasses. Particularly, there are solutions that use color separation, light separation and time division methods to be used in cooperation with the 3D glasses.
Recently, time division method is most widely used, and it generally relates to an active shutter-based 3D display approach in which images of left and right eyes are alternately displayed in a temporal sequence and also an infrared synchronization signal transmitter and shutter glasses cooperate therewith to present a stereoscopic image. The structure of a system using the active shutter-based 3D display approach is illustrated in FIG. 1, and generally includes a display device, a computer, an infrared transmitter and shutter glasses. In this approach, the display device displays 3D data at a frame frequency of 120 Hz. Particularly 60 frames of images of the left eye and 60 frames of images of the right eye are alternately displayed in a temporal sequence, and since each frame includes data refresh time and data hold time (T in FIG. 2 represents the time of one frame of image). During the Vertical Blanking Interval (VBI) time in FIG. 2, the left eyeglass L of the shutter glasses is opened (the opened status represents a status at which light can be transmitted) when refreshing of the left eye (L1, L2, etc., in FIG. 2) is finished. As shown, the data hold time (VBI) arrives after each image frame of the left eye has been scanned. Similarly, the right eyeglass R of the shutter glasses is opened when the data hold time (VBI) arrives after each frame of image of the right eye (R1, R2, etc., in FIG. 2) has been scanned As illustrated in FIG. 2, response time Ton of liquid crystals when the eyeglass is opened and response time Toff of the liquid crystals when the eyeglass is closed are included. The shutter glasses are synchronized with the display device in timing sequence through the infrared transmitter in cooperation with an infrared receiver integrated on the shutter glasses. This approach can separate the images of the left eye to achieve the 3D effect.
However, since the eyeglasses of the shutter glasses typically include a liquid crystal display, and the response time of liquid crystals is on the order of ms, a minimum period of time for the eyeglasses to be open or closed completely is required. In addition, the shutter glasses are open only in the VBI time and thus there is a greatly shortened time for response remaining for the liquid crystals. Accordingly, there is a loss of brightness because the opening of the eyeglasses is delayed due to the response time required for the liquid crystals. In addition, there is a delay in closing the eyeglasses due to the response time required for the liquid crystals, so that the images of the left and right eyes may be visible at the same time to an observer, thus resulting in a problem of considerable crosstalk between the images of the left and right eyes, tending to cause a residual image and lowering the effect of a dynamic image.
Furthermore, the following drawbacks may result from the shutter glasses using liquid crystal. The cumbersome glasses may make a user uncomfortable after wearing the glasses for a long period of time and may be further inconvenient particularly to those with nearsighted glasses. In addition, the glasses are electronic devices with rechargeable lithium battery and therefore release electromagnetic radiation. Furthermore, the battery is at a risk of explosion. The glasses are signal-synchronized through the infrared receiver with the infrared transmitter connected to the computer, and an infrared signal may be interrupted if the propagation path of the signal is hindered, thus degrading the display effect. The glasses are costly, have a short service period, are easily damaged and have high usage cost. A 3D display system in the prior art for which the shutter glasses are required is costly due to the foregoing drawbacks of the glasses.